Amplification of Risk Caused by Mis-Routing of DNA Double-Strand Break Repair

DNA 双链断裂修复路径错误导致的风险放大

• 批准号: 8063644
• 负责人: Anna L Malkova
• 金额: $ 26.42万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8063644
• 关键词: Affect; Anaphase; Animal Model; Antineoplastic Agents; Cells; Centromere; Characteristics; Chromatids; Chromosomal Breaks; Chromosomal Rearrangement; Chromosome Breakage; Chromosome abnormality; Chromosomes; Complex; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Sequence Rearrangement; DNA biosynthesis; Data; Development; Double Strand Break Repair; Environmental Risk Factor; Etiology; Event; Exposure to; Frequencies; Gene Amplification; Gene Rearrangement; Genetic; Genetic Recombination; Genome; Genomic Instability; Genomics; Goals; Health; Hereditary Disease; Human; Interruption; Knowledge; Laboratories; Lead; Maize; Malignant Neoplasms; Mammals; Mediating; Methods; Molecular; Mutation; Outcome; Pathway interactions; Pharmaceutical Preparations; Process; Research; Research Personnel; Risk; Role; Saccharomyces cerevisiae; Series; Simulate; Site; Source; Structure; System; Testing; Work; Yeast Model System; Yeasts; assault; base; cancer cell; dimer; expectation; experience; high risk; innovation; mutant; neoplastic cell; prevent; repaired; research study; telomere

DESCRIPTION (provided by applicant): Double-strand DNA breaks (DSBs) are dangerous for human health because imprecise or faulty repair often leads to mutations and chromosome aberrations causing genetic diseases and cancer. The long-term goal of the investigator is to develop ways to minimize genomic instability resulting from DSBs. It is essential for this purpose to establish how DSB repair is executed and regulated, and how it leads to genome destabilization. The aim of this project is to unravel a number of molecular mechanisms capable of amplifying the consequences of DSBs in the model organism Saccharomyces cerevisiae. Firstly, this proposal is focused on chromatid fusions, which amplify the destabilizing effect of a single DSB by channeling it into breakage-fusion- bridge (BFB) cycles that create a series of rearrangement-prone secondary DSBs. Preliminary data allowed the investigator to propose that chromatid fusions can be stimulated by DSBs by allowing inter-molecular single-strand annealing (SSA) between inverted DNA repeats (IRs). Genetic methods and physical analyses of molecular intermediates are proposed to investigate this, as well as other homology-driven pathways of chromatid fusions that are currently poorly understood. Second, this proposal will unravel the mechanisms that allow broken chromosomes to acquire telomeres. Preliminary data suggested that break-induced replication (BIR) is the primary mechanism by which chromosomes undergoing BFBs are stabilized, which makes BIR the primary source of BFB-associated GCRs such as deletions, amplifications, and translocations. This research will specifically investigate the formation of translocations, which is the most deleterious outcome of BIR. Finally, results from genetic studies led to the hypothesis that interruption of BIR or other aberrant processing of BIR intermediates results in new chromosomal breakages that lead to cascades of DNA instability similar to the non-reciprocal translocations (NRTs) pathway known to amplify the number of rearrangements that result from an initial DSB in mammals. Thus, this proposal represents the first yeast model capable of simulating mammalian NRTs and is intended to unravel the molecular mechanisms of this process. In addition, the effects of genetic and environmental factors on channeling BIR repair into the GCR-producing pathways will be investigated. In summary, this research will elucidate the molecular mechanisms by which DSB repair can result in genomic consequences more destructive than the initial breakage. It is proposed that chromatid fusions, BIR, and NRTs are three such processes capable of amplifying the risks caused by a DSB due primarily to triggering BFB cycles. Further, experiments are proposed to test whether the magnification of damage that results from these genome-destabilizing DSB repair processes could be further amplified by cellular exposure to various environmental factors. To this end, experiments are planned to test the effects of various DNA damaging agents, including anti-cancer drugs, to investigate whether these agents might increase the frequency of high-risk repair processes or otherwise alter their outcomes. PUBLIC HEALTH RELEVANCE: This research is aimed to unravel the molecular mechanisms that lead to genomic destabilization by channeling double-strand DNA breaks into chromosomal rearrangements. Because genetic aberrations are a hallmark of cancer cells, this research will further our understanding of the etiology of some cancers.

描述（由申请人提供）：双链DNA断裂（DSB）对人类健康是危险的，因为不精确或错误的修复通常会导致突变和染色体畸变，导致遗传疾病和癌症。研究人员的长期目标是开发方法来最大程度地减少DSB引起的基因组不稳定性。对于此目的，必须确定如何执行和调节DSB修复以及如何导致基因组不稳定。该项目的目的是揭示许多能够扩增酿酒酵母模型中DSB的后果的分子机制。首先，该建议集中在染色质融合上，通过将单个DSB引导到断裂融合桥（BFB）循环中，从而扩大了单个DSB的不稳定效果，从而产生一系列重排的次级次级DSB。初步数据允许研究者提出，DSB可以通过允许倒置DNA重复序列（IRS）之间的分子间单链退火（SSA）来刺激染色单体融合。提出了对分子中间体的遗传方法和物理分析来研究这一点，以及目前知之甚少的染色单体融合的其他同源驱动的途径。其次，该提案将揭示允许破裂染色体获取端粒的机制。初步数据表明，断裂诱导的复制（BIR）是稳定BFB的染色体的主要机制，这使得BIR成为BFB相关GCR的主要来源，例如缺失，扩增和易位。这项研究将特别研究易位的形成，这是BIR最有害的结果。最后，遗传研究的结果导致假设，即BIR或其他异常处理的BIR中间体的中断导致新的染色体断裂，导致DNA不稳定性类似于与非逆转录易位（NRTS）途径相似的，该途径已被扩增，该途径会放大了由最初DSB中的最初DSB中重建的重新分析数量。因此，该建议代表了能够模拟哺乳动物NRT的第一个酵母模型，并旨在揭示该过程的分子机制。此外，将研究遗传和环境因素对将BIR修复引入产生GCR的途径的影响。总而言之，这项研究将阐明DSB修复可以导致基因组后果比初始破裂更具破坏性的分子机制。有人提出，染色单体融合，BIR和NRT是三个这样的过程，能够扩大主要是由于触发BFB周期的DSB引起的风险。此外，提出了实验来测试这些基因组二动DSB修复过程造成的损害的放大，可以通过暴露于各种环境因素的情况下进一步扩大。为此，计划进行实验，以测试包括抗癌药物在内的各种DNA损害药物的影响，以研究这些药物是否可能增加高危修复过程的频率或以其他方式改变其结果。 公共卫生相关性：这项研究的目的是通过将双链DNA断裂到染色体重排中，从而揭示导致基因组不稳定的分子机制。由于遗传像差是癌细胞的标志，因此这项研究将进一步了解某些癌症的病因。